Our protagonist is a girl named Setsuna Shindo.
At first glance, she's just a normal high school student, but after school and on her days off, she's a sister of the Central Church along with her older sister, Yuka.

However, that's not all they are...
Sisters by blood and Sisters of the church, there's a darker side to their duties:

"EXORCISM"

The dispelling of vile demonic forces that have carved their way into the bodies of innocent humans. Cases of possession have been on the rise as of late, and as the thought surfaced as to whether this was some kind of Dark Premonition... Yuka would find herself kidnapped by a mysterious organization, leaving no trace of her whereabouts. Setsuna searches for her missing sister, helped by the head priest of the church, and her childhood friend, Toma Kitagawa.

Yuka's captors initiate their search for Setsuna as well, and this will mark the beginning of her Eternal Purgatory of Vile Lust...​